1994 Mercedes Benz 350sdl

Engine Performance problem
1994 Mercedes Benz 350sdl 6 cyl Two Wheel Drive Automatic 287000 miles

I have noticed the car is very sluggish going uphill or when I try to merge into fast traffic. Could it be the fuel filter? And are there 2 filters and where are they located?
August 15, 2010.

Lack of acceleration, chugging, hesitating, bogging, misfiring etc. Could be caused by one of the following below: Start here-inspect and test all the items below: Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard it.

Aug 15, 2010.